37-bus, 123-bus, and 8500-bus systems are multi-phase. In each network, the feeder or substation is selected as the slack bus (bus 0). The historical data have been preprocessed by the GridLAB-D [1]}, an open source simulator for distribution grid. The load profile from PG&E is used to simulate the power system behavior in a practical pattern. This profile contains anonymized and secure hourly smart meter readings over \(110,000\)  PG&E residential customers for a period of one year spanning from 2011 to 2012. Since both 37-bus and 123-bus systems are primary distribution grids, the real power at each bus is an aggregation of \(10 - 100\)  customers. The load buses in both systems are unnecessary to be multi-phase. The details of bus and branch phases are given in [2]}. The voltage data at each bus are used for topology estimation. Fig. REF  summarizes the overall process of topology estimation and bus phase identification.
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